The utility model has the functions of high temperature shrinkage, soft flame retardant, insulation and corrosion prevention. When the utility model is heated, the inner diameter of the sleeve is rapidly shrunk to half, and the protected electronic component is tightly wrapped in the casing to protect the electronic component, and the utility model has the function of insulation and temperature resistance. The utility model has the functions of high temperature shrinkage, soft flame retardant, insulation and corrosion prevention. When the utility model is heated, the inner diameter of the sleeve is rapidly shrunk to half, and the protected electronic component is tightly wrapped in the casing to protect the electronic component, and the utility model has the function of insulation and temperature resistance.